The present invention relates to facsimile apparatus and more particularly to a facsimile apparatus capable of reading image information and recording the same with a marked high image quality.
In a conventional facsimile apparatus, reading and recording are performed by scanning image information line by line; therefore, a reading element and a recording element for one line are required; and, accordingly, a great number of scanning elements and elements for the driving circuits are required in the conventional facsimile apparatus.
To be more specific, when read scanning and record scanning of an A4 (210.times.297 mm) size sheet are performed with an 8 lines/mm scanning line density, the reading and recording elements for 1728 bits are required, and, furthermore, transistors, resistors and condensers for driving the read and scanning elements are required. As a result, a great number of elements are required.
In the case where a head for scanning one line is constructed by aligning scanning elements in the main scanning direction, it is difficult to produce such a head accurately. Therefore, a head capable of covering half or one third of one line is conventionally used so that reading and recording of one line of image information are performed by shifting the head so as to cover the whole line. However, this system has a shortcoming in that the points of junction of each scanning part become uneven.
Furthermore, in the case of a facsimile apparatus of the type in which the scanning is performed line by line, the original or the recording sheet has to be fed line by line or several lines at a time mechanically using a motor to perform subscanning. In a facsimile apparatus of this type, however, the feeding speed varies due to the inertia of the motor when the scanning starts or stops. As a result, the space of each scanning line varies so that it is difficult to obtain good images.
The applicants of the present invention have proposed a facsimile apparatus capable of performing the read and record scanning, with the above-mentioned conventional shortcomings eliminated, in U.S. patent application Ser. No. 967,834 filed Dec. 18, 1978, and German Patent Application O.S.L. 2,854,845 filed Dec. 19, 1978.
Referring to FIG. 1, there is perspectively shown the facsimile apparatus disclosed in the United States Patent Application and the German Patent Application. FIG. 2 is a schematic cross section of the facsimile apparatus of FIG. 1. As shown in the figures, the facsimile apparatus comprises a scale plate 1 which is fixed to the apparatus, a carriage 2 which is disposed so as to be capable of reciprocating along the scale plate 1 and a D.C. motor 3 for driving the carriage 2.
On the plate 1, there are disposed slits 1a for regulating the main scanning position at the time of reading and recording, and slits 1s and 1e for defining an effective image width in which the read scanning and the record scanning are effective.
On the carriage 2, there are disposed a reading head 2a, a recording head 2b and a detector 2c for taking out a slit detection signal as the carriage moves along the plate 1.
To be more specific, on the reading head 2a, there are arranged reading elements for a plurality of bits for reading a plurality of lines in the subscanning direction from an original O, and the reading head 2a is designed so that an image corresponding to the image of the original O at the main scanning position is formed on the reading head 2a.
Furthermore, on the recording head 2b, there are arranged styli for recording image information for a plurality of lines in the subscanning direction on a recording sheet S.
In the detector 2c, there are arranged a light emitting element 2c1 and a light receiving element 2c2 in such a manner that they face each other across the plate 1 and a predetermined signal is detected from each slit by the light emitting element 2c1 and the light receiving element 2c2 as they move.
In FIG. 1 and FIG. 2, reference numeral 4 represents pulleys, reference numeral 5a and 5b guide bars and a wire for reciprocating the carriage 2 by the D.C. motor 3, reference numeral 6 sheet transfer rollers, reference numeral 7 a contact glass, reference numeral 8 a counter electrode, and reference numeral 22 a lamp for illuminating the original O, which is attached to an optical system 21.
By this construction, the carriage 2 is reciprocated by the D.C. motor 3 to perform the main scanning and when the original O or the recording sheet S is fed in the direction of the arrow to perform the subscanning, the image information for a plurality of bits in the subscanning direction is read or recorded in accordance with the signal obtained from the detector 2c. Thus the image information for a plurality of lines can be processed by one main scanning. Therefore, the subscanning of the original O or of the recording sheet S can be performed a plurality of lines at a time and, furthermore, the main scanning can be performed when the original O or the recording sheet S is stopped. As a result, the reading and recording of the image information can be done, while each scanning line is set parallel to each other.
Furthermore, in this facsimile apparatus, it is possible to reduce the number of the read and record scanning elements significantly, specifically down to the number of elements necessary for 64 bits in this case when other necessary conditions are taken into consideration and, accordingly, the number of circuit elements can be reduced. As a result, the total number of necessary elements can be reduced, helping to lower the cost of the facsimile apparatus.
In this facsimile apparatus, however, it is required that the carriage 2 be reciprocated at a constant speed the full width of the effective image area and, therefore, a tachometer generator or tachometer dynamo is attached to the D.C. motor 3 so that the rotation speed of the D.C. motor is controlled by the signal generated from the tachometer generator.
Therefore, the facsimile apparatus has a better function and effect than that of the conventional facsimile apparatus, but it requires such an additional device as the tachometer generator, making the facsimile apparatus nevertheless still more expensive than the conventional facsimile apparatus.